dt-bindings: ti-sysc: Add SPDX license identifier

Add the appropriate SPDX license identifier to the common
TI sysc bindings header file.
Signed-off-by: Suman Anna <s-anna@ti.com>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

include/dt-bindings/bus/ti-sysc.h

+/* SPDX-License-Identifier: GPL-2.0 */
 /* TI sysc interconnect target module defines */
 
 /* Generic sysc found on omap2 and later, also known as type1 */